Love my Nook Color as an e-reader. I have the Kindle App and the Nook App on it to let me read form either store. Its the right size for reading, and since I do most of my reading at night in bed, the LCD far better then E-Ink, IMO. Like it so much we bought two of them, one for my wife, and one for me.
We both uses ours every day to read books.
For a tablet? Eh, I guess... but I have an Asus Transformer for my tablet (and netbook) and it can not compete with at that level.